Cooling arrangement for gas turbines



March 11, 1941. A. E. GIBSON COOLING ARRANGEMENT FOR GAS TURBINES Inventor. Aha-t E. Gibson, Fan/' Filed June 28, 1939 Plus Attorney.

Patented Mar. 11, 1941 UNITED STATES coouNc ARRANGEMENT FOR GAS runnmas Albert E. Gibson, Lynn,

Mass assiznor to Gencral Electric Company. a corporation of New York Application June 28, 1939, Serial No. 281,551

3 Claims.

, The present invention relates to cooling arrangements for gas turbines and particularly of the type of turbines which include a bucket wheel supported on an overhung shaft as are used on aircraft for driving a supercharger or generator. These turbines are usually supplied with gases discharged from combustion engines at temperatures of 750 C. and above. At these high temperatures the turbine bucket wheel may be excessively heated and the safety of an aircraft thereby endangered. In order to avoid such excessive heating of the bucket wheel a cooling device for conducting cooling air to the bucket wheel may be provided.

The object of my invention is to provide an improved construction and arrangement of the type of turbines above specified whereby the turbine may be safely operated with gases at high temperatures.

For a consideration of what I believe to be novel and my invention, attention is directed to the following description and the claims appended thereto in connection with the accompanying drawing.

In the drawing, Fig. 1 illustrates a view partly in section of a gas turbine arrangement embodying. my invention, and Fig. 2 is a front view of Fig. 1.

The arrangement comprises a gas turbine with a bucket wheel Ill having a rim ii to which an annular row of buckets I2 is secured. The outer ends of the buckets are connected by a band l3. The wheel has a solid disk secured to an overhung shaft It which is supported by a bearing l5 forming a part of a supercharger or like machine. Operating gases are conducted to the bucket wheel by a nozzle box 16 which has an inlet II for connection to a source of supply and a plurality of blades 18 forming nozzles for properly directing the gases towards the buckets l2 of the wheel. Radiation of heat from the nozzle box l6 towards the bearing l5 and other adjacent elements is reduced by a protectingor heat insulating wall l9, which latter may also serve as a support for the nozzle box.

The discharge side 01. the bucket wheel is enclosed by a shield 20 with a. flange 2| secured to the nozzle box I6 by bolts 22. The shield 20 forms a channel 23 for receiving gases issuing from the bucket wheel and conducting them to an outlet 24 formed in the present instance by a lower portion of the shield 20. Thus the shield 20 broadly constitutes an exhaust casing for the gas turbine.

The arrangement includes means for protecting the central portion of the bucket wheel, that is. the bucket wheel disk, from the heat 0! the gases issuing from the wheel. This protecting means comprises a double-walled cap having an inner wall 25 and an outer wall 26. The two I walls are spaced, thus forming an annular channel 21. Both walls are secured together and supported on the shield 20 by means including a plurality oi partitions 28. The two walls ,are somewhat conically-shaped with the outer wall surrounding and extending beyond the inner wall towards the bucket wheel to form a small clearance therewith. The inner wall 25 forms a space 29 with the bucket wheel and has a central portion opening into an inlet conduit 30 which is partly formed by the shield 20. The space 21 formed between the two walls communicates at its outer end with the space 29 and at its inner end with the atmosphere through an opening 3| in the shield 20. During operation, cooling air is conducted through the conduit 30 to the space 29 where the air effects cooling of the wheel and is discharged at the outer portion of the space 29 through the space 21 and the opening 3| into the atmosphere. The shield may be positioned so that the inlet conduit 30 receives cooling air directly from the slip stream of the aircraft. Thus the shield or exhaust casing 20 according to my invention has an opening 24 through which gases issuing from the turbine wheel II) are discharged and another opening which preferably is located near the center .of the turbine wheel for receiving cooling air from the conduit 30. This cooling air is' conducted to the wheel and discharged therefrom by means including two concentrically spaced walls 25 and 26, the wall 25 being connected to the conduit 30 to receive cooling air therefrom and the wall 26 being connected to the shield 20 to discharge the cooling air through the opening 3|.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. Gas turbine arrangement comprising a turbine wheel having a rim and a row of radial buckets secured thereto, an exhaust casing having a discharge opening and enclosing the discharge side of the turbine wheel to conduct gases issuing therefrom through the opening, and means located within the exhaust casing for cooling 'a central portion of the wheel comprising a cooling cap having an inner wall adjacent a central portion of the wheel to form a cooling space therewith, a conduit projecting through the casing for conducting cooling air to said space and an outer wall surrounding in spaced relation the inner wall and having an outer edge closelyi spaced with the rim and an inner edge connected to another opening of the casing to form a channel for discharging cooling air from that space into the atmosphere.

2. Gas turbine arrangement comprising a turbine wheel having a rim and buckets secured thereto, an exhaust casing having an opening for discharging gases issuing from the wheel and another opening for receiving cooling air to be conducted to the wheel, and means for directing air conducted to the other opening to the wheel and for discharging the air into the atmosphere, said means comprising inner and outer substantially conically-shaped spaced walls disposed within and supported on the exhaust casing, a conduit projecting through the other opening and connected to the inner wall, the outer wall having an outer edge portion surrounding the inner wall and closely spaced with the rim and an inner edge connected to the other opening.

3. On an aircraft a gas turbine arrangement comprising a turbine wheel having a rim and a row of buckets secured thereto with an axis oi rotation substantially perpendicular to the direction oi the slip stream, an exhaust casing enclosing the discharge side of the wheel with a first opening adjacent a central portion 01' the wheel and a second opening in the direction of the slip stream for conducting gases discharged from the wheel to the atmosphere, and means for cooling the wheel comprising a cap disposed within the casing adjacent a central portion of the wheel to form a cooling space therewith, a conduit with an inlet for receiving cooling air from the slip stream and an outlet connected to the cooling cap, and means for discharging cooling air from the cooling space to the atmosphere comprising a wall spaced from and surrounding the cooling cap to define an annular channel therewith, said wall having an outer edge portion closely spaced with the rim and an inner edge connected to the first opening.

ALBERT E. GIBSON. 

